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German index-linked rent — adjusting to the consumer price index

Under an index-linked lease the rent follows the Federal Statistical Office's consumer price index. It must stay unchanged for at least a year, and the adjusted rent is payable from the start of the month after next following receipt of the notice.

2026 rules — verified on September 23, 2026Free, no account

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Sources and assumptions

  • gesetze-im-internet.de — BGB § 557b Abs. 2 Satz 1 — tax year 2026, verified on September 23, 2026
    Excerpt from the source : « Während der Geltung einer Indexmiete muss die Miete, von Erhöhungen nach den §§ 559 bis 560 abgesehen, jeweils mindestens ein Jahr unverändert bleiben. »
  • gesetze-im-internet.de — BGB § 557b Abs. 3 Satz 3 — tax year 2026, verified on September 23, 2026
    Excerpt from the source : « Die geänderte Miete ist mit Beginn des übernächsten Monats nach dem Zugang der Erklärung zu entrichten. »

Calculation assumptions

  • Rent moves in proportion to the index change (rent × new index ÷ old index). BGB s. 557b prescribes no formula; the clause in the lease prevails.
  • Index values are inputs: Destatis publishes them monthly, they are not in the statute.
  • Increases under BGB ss. 559 to 560 (modernisation, service charges) are left out; an increase under s. 558 is barred for index-linked rents.
  • Stepped rent (BGB s. 557a) is not covered: each step must also last at least a year, but the amounts are already fixed in the lease.

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This result is provided for information purposes only and does not constitute personalised tax advice. Check your situation with the tax authorities or a professional.